The electrical connector art provides many structures and methodologies to satisfy requirements of specific uses and overcome certain problems associated with establishing secure static connections in particular environments. Generally, it is desirable to stabilize the position of an electromagnetic/electrical connector in order to preserve the integrity of cable/connector interface against vibration and other shock forces. Strain relief assumes heightened importance in vehicular environments due to harsher conditions. For example, aircraft bulkhead feedthrough pin-terminal arrays must be secured against intensified environmental vibration and shock.
Irregularities in installation of electromagnetic conduit connections are of concern in addition to environmental factors. During cable connection installation and maintenance activities, the installer may unintentionally stress a conduit connector interface by using uneven or non-uniform forces. Thus, the cable/connector interface can be stressed during assembly or repair procedures when the conduit is twisted or torqued. In the absence of practiced installation care, the installation process, itself, may impart undesirable torquing force on the conduit which may compromise the electrical connection by damaging the internal cable wires/fibers or cable insulation and corrupting the electrical isolation of cable wires or the pin connections. Consequently, hazardous situations may be created.
In order to protect against unnecessary cable connector damage, strain relief adjuncts have been developed in response to the strain relief problem. Tape wrapping is the most typical strain relief adjunct where the installer wraps insulating tape around the junction of the cable and connector for a select downstream (distal) distance of the cable. The thickness of the tape wrapping governs the degree of enhanced rigidity. Therefore, the tape is wrapped to provide a sufficient number of windings to achieve for the desired strain relief around the cable-connector interface.
The act of winding tape around the cable, itself, generates uneven radial pressures on the internal wire(s)/fibers which can damage fine wires, and fine pin connections and variations inevitably occur during such tape winding. For example, the quantity of tape used and wrapping quality are not necessarily uniform. The number of windings, the winding technique, the skill of the installer, and the conditions at the wrapping situs (a confined or open space), all contribute to differences in the quality and quantity of strain relieving tape wrap. Even non-technical factors such as fatigue of the installer can affect tape wrapping applications and contribute to non-standardization.
The costs associated with non-standardized, custom wrapped, and special tapes used for strain relief--labor, material, and disposal--cannot be ignored. The labor costs associated with tape wrapping, both in original installation and in subsequent repair and modification procedures, may become significant, particularly in confined or dangerous environments. Disposal of used tape may also present an environmental control problem. The tape composition itself may constitute a regulated waste material (halocarbon polymers) or the environment in which the tape has been used may contaminate the discarded tape thereby requiring disposal subject to hazardous waste controls.
As noted, when used in relatively rugged environmental conditions (high vibration environments and the like, e.g. air and space vehicles, military applications, etc.) electrical connector strain relief takes on increased importance which has led to the development of special adjuncts. For example, harness/"horse collar" assembly with a stand-off split ring/tape grommet have been developed for use with backshell connectors used in vehicles. A typical, prior art, split ring/grommet "horse collar" assembly (A), is illustrated in FIG. 3. The assembly (A) includes four components, which may be independent or integrated. The assembly includes: 1) a nut standoff connection (N), generally threaded, to the backshell connector (B); 2) a rearwardly projecting standoff or arm (generally as a pair) (S); 3) a split/hinged clamping ring (R) connected to the rearward end of the standoff and; and 4) a tape grommet (TG) formed from a sufficient number of windings so that the outer diameter of the tape windings matches the inner diameter of the clamping ring. The expression "horse collar" designates the combination of the threaded nut, standoff, and split ring combination.
To establish the strain relieving backshell "horse collar" assembly, the installer connects (screwing or clamping) the nut/standoff member (N) to the backshell, taping the cable exterior in the area underlying the split ring (R) to form a custom tape winding grommet (TG), and screwing/clamping the split ring segments together to radially engage and compress the tape windings onto the cable. A compression fit is achieved by engaging the inner surface of the clamping ring onto the outer surface of the tape windings. By tightening the screws, the spilt ring clamps radially onto the tape grommet to relieve strain and positionally stabilize the cable relative to the backshell and connector.
The resulting assembly reduces cable tension at the connector interface by providing some slack in the cable between the clamping ring and the connector (i.e., coextensive with the standoff). Therefore, the combination of the horse collar, split ring, and tape windings serve to prevent downstream stress on the cable from dislodging the wires from the backshell connector terminal.
Notwithstanding the advantages provided by the above-referenced horse collar, backshell connector/tape assembly, such an arrangement still requires tape winding. Accordingly, it suffers from the shortcomings identified above, with respect to using tape wrapping to provide strain relief.